The present invention relates to a welder apparatus having a feature of a compact combination of a weld control transformer and weld control unit.
Typical welder apparatus are resistance welders or arc welders. Such welders are widely used in many manufacturing industries. In particular, those welders are indispensable in an automobile industry, for performing welding of thin steel plates of car bodies.
FIG. 11 shows a basic configuration of a conventional resistance welder which is formed of gun 1 having welding electrodes, weld transformer 2, and weld control unit 3. In recent years, there is a large demand for a compact resistance welder constituted by two components, one of which is an assembly of gun 1 and transformer 2, and the other of which is control unit 3.
In a resistance welder conventionally used in the automobile industry, gun 1, weld transformer 2, sequencer 4, and program unit 5 are installed near conveyer line C, as is shown in FIG. 12, while only weld control unit 3 is installed in a mezzanine separated from conveyer line C. For this reason, a physical distance between control unit 3 and conveyer line C often becomes several tens meters and, therefore, it is necessary to install long power cable 6 between unit 3 and transformer 2, long signal cable 7 between unit 3 and sequencer 4, and long signal cable 8 between unit 3 and unit 5.
In a recent automobile industry, multispots welding has been widely employed. In multispots welding, a car body, i.e., a workpiece to be welded, is fixed by a jig, and many spots of the workpiece are simultaneously welded by a gun having many welding electrodes, using an industrial robot.
In the above-mentioned conventional welder, the gun, weld transformer, weld control unit, sequencer, and program unit are arranged separately. Therefore, in order to achieve signal transmission among the above transformer and units, many long cables must be installed, posing problems of installation cost and installation space, etc.. Further, when multispots welding is performed, many components (the gun, transformer, sequencer, and program unit) must be arranged with their specific correlation. Then, modification of welding conditions, installation of each component, and/or maintenance thereof becomes a laborious work.